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初貝 安弘 筑波大学筑波大学大学院 数理物質科学研究科 物理学専攻 教授 初貝写真
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ResercherID: Y.Hatsugai
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投稿者 : hatsugai 投稿日時: 2019-01-04 13:31:15 ( 6656 ヒット) Our paper "Weyl points of mechanical diamond ", by Yuta Takahashi, Toshikazu Kariyado, Yasuhiro Hatsugai, has been published in Phys. Rev. B at the beginning of the year 2019. Weyl equation (massless Dirac equation) is applied for a description of the classical Newton dynamics with periodic structure, implying non-trivial edge states due to bulk-edge correspondence. 投稿者 : hatsugai 投稿日時: 2018-07-31 07:27:44 ( 7435 ヒット) New topological number as an entanglement polarization for the topological quadrupole phases is defined and its validity is demonstrated, T. Fukui and Y, Hatsugai, Phys. Rev. B 98, 035147, (2018) . It picks up dipolar components of quadrupole phases which are canceled out in total. 投稿者 : hatsugai 投稿日時: 2018-04-20 18:51:10 ( 7347 ヒット) 投稿者 : hatsugai 投稿日時: 2017-10-06 16:36:02 ( 7702 ヒット) The entanglement Chern numbers is a Chern number of an entanglement Hamiltonian which characterizes topological properties of a topological phase. Starting from a pure state density matrix of the ground state, one may obtain finite temperature (mixed state) density matrix by tracing out parts of the system. If the entanglement hamiltonian has a finite energy gap, the Chern number is well defined by lowering the temperature. We apply the concept for the 3D topological phases.The parity of the number of the Weyl point gives a well defined topological number to distinguish the the state is topologically non trivial. Have a look at arXiv 1708.03722 . The paper has been accepted for publication in Physical Review B. 投稿者 : hatsugai 投稿日時: 2017-08-17 17:01:30 ( 7677 ヒット) 初貝研究室では今回助教2名を公募いたします(公募締め切り2017年9月15日)。委細は [助教公募] をご確認ください。適任者のご推薦、ご応募の方よろしくお願いいたします。
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現在の時刻
今年もやります。まずは 量子力学3(遠隔).
冬は
統計力学2 改め物性理論II (大学院「ベリー接続の理論とバルクエッジ対応」).
令和二年の新年あけましておめでとうございます。今年もあと-1183日!
最新ニュース
投稿者 : hatsugai 投稿日時: 2020-11-03 10:00:50 ( 4760 ヒット) Thouless' (adiabatic) pump in one-dimension is a typical topological phenomena characterized by the Chern number that correspondes to the quantized motion of the center of mass (COM). Although the COM is only well-defined with boudary (to set the origin of the coordinate), the COM experimentally observed is given by the bulk and the edge states do not contribute. Ultimate adiabaticity, that has never been achieved experimentaly, supports the quantization of the COM supplemented by the periodicity of the system with boundaries. This is the unique bulk-edge correspondence of the pump. We here propose a generic construction using a phase boundary line of the symmetry protect phase with two parameters works as a topological obstruction of the pump in extended parameter space. The construction is purely of manybody and the interaction can be one of the parameters. Have a look at "Interaction-induced topological charge pump" by Yoshihito Kuno and Yasuhiro Hatsugai, Phys. Rev. Research 2, 042024(R), (2020) (Open access) 投稿者 : hatsugai 投稿日時: 2020-10-01 16:07:56 ( 5231 ヒット) Motivated by a historical example, the Dirac Hamiltonian as a square-root of the Klein-Gordon Hamiltonian, its lattice analogue has been discussed recently. Zero energy states are shared by the parent and its descendant. The story is more than that. Not necessarily zero energy but its high energy part can also share topological characters. We hereby propose a “square-root higher order topological insulator (square-root HOTI)” when its squared parent is HOTI. Based on the simple observation that square of the decorated honeycomb lattice is given by a decoupled sum of the Kagome and honeycomb lattices, we have demonstrate that the “corner states” of the breezing Kagome lattice with boundaries share topological characters with its descendant as the decorated honeycomb lattice. Have a look at our recent paper just published online, "Square-root higher-order topological insulator on a decorated honeycomb lattice" by Tomonari Mizoguchi, Yoshihito Kuno, and Yasuhiro Hatsugai, Phys. Rev. A 102, 033527 (2020), also arXiv:2004.03235. 投稿者 : hatsugai 投稿日時: 2020-08-16 14:53:28 ( 5424 ヒット) Adiabatic deformation of gapped systems is a conceptual basis of topological phases. It implies that topological invariants of the bulk described by the Berry connection work as topological order parameters of the phase. This is independent of the well-established symmetry breaking scenario of the phase characterization. Adiabatic heuristic argument for the fractional quantum Hall states is one of the oldest such trials that states the "FRACTIONAL" state is deformed to the “INTEGER”. Although it is intuitive and physically quite natural, there exist several difficulties. How the states with different degeneracy are deformed each other adiabatically? We have clarified the questions and demonstrated this adiabatic deformation on a torus in the paper "Adiabatic heuristic principle on a torus and generalized Streda formula" by Koji Kudo and Yasuhiro Hatsugai , Phys. Rev. B 102, 125108 (2020) (also arXiv:2004.00859) What is deformed continuously is a gap not the states ! This is also sufficient for the topological stability of the Chern number (of the degenerate multiplet) as a topological order parameter. Have a look at. 検索
バルク・エッジ対応
- [0] バルクとエッジ
- [1] 集中講義
- [2] 原論文と解説
- [3] トポロジカル秩序とベリー接続:日本物理学会誌 「解説」 [JPS-HP] [pdf]
- [4] "Band gap, dangling bond and spin : a physicist's viewpoint" [pdf] [Web]
トポロジカル相
[0]昔の科研費 - 科研費 1992年度:電子系スピン系におけるトポロジカル効果
- 科研費 1994年度:物性論におけるトポロジーと幾何学的位相
私の講演ファイルのいくつか- [1] MIT, Boston (2003)
- [2] APS/JPS March Meeting (2004)
- [3] JPS Fall meeting, JAPAN (2004)
- [4] APS/JPS March meeting (2005)
- [5] JPS Fall meeting (2005):Entanglement
- [6] Superclean workshop, Nasu (2006)
- [7] MPIPKS, Dresden (2006)
- [8] KEK, Tsukuba (2007)
- [9] ETH, Zurich (2008)
- [10] ICREA, Sant Benet (2009)
- [11] JPS Meeting, Kumamoto (2009)
- [12]HMF19, Fukuoka (2010)
- [13] NTU, Singapore (2011)
- [14] ICTP, Trieste (2011)
- [15] Villa conf., Orland (2012)
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